When using a device with dual cameras, I don’t see an option to switch which camera Kami uses for recording video comments. Am I blind?
You’re not blind. When you choose video comment, and then select the document, it just starts recording. It doesn’t ask what camera you want to use, nor is there a flip/switch button.
Well, that’s pretty useless. 
It basically just means on my device it’s now a higher-bandwitch audio comment. I have a session with the Kami rep tonight, so I plan to ask about this. If I learn a workaround, I will post it here.
I found this on Reddit and it works. “Hey, can I just ask what browser you’re using? If you’re using Chrome and most Chromium derivatives (including Edge Chromium), you should be able to go to chrome://settings/content/camera (you’ll need to copy that into your URL bar) and then switch the camera there.”